Properties of Cosmic Aluminum Nuclei: Results from the Alpha Magnetic Spectrometer

We report the properties of aluminum (Al) nuclei in cosmic rays measured in the rigidity range 2.15 GV to 3.0 TV with 0.51 million nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. We observed that above 6 GV the Al spectrum is well described by the weighted sum of the silicon spectrum (primary cosmic rays) and the fluorine spectrum (secondary cosmic rays). The fraction of the primary component increases with rigidity and becomes dominant at highest rigidities. Al/Si abundance ratio at the source is determined independent of cosmic ray propagation.